Add "Send to..." context menu item to mouse.el

* lisp/send-to.el: New package implements sending files/region.

* lisp/mouse.el (context-menu-send-to): Add "Send to..." context menu.

* lisp/term/ns-win.el (ns-send-items): Expose native macOS send API.

* src/nsfns.m (ns-send-items): Implement native macOS sending.

* etc/NEWS: Announce the new feature.

etc/NEWS

@@ -229,6 +229,13 @@ that your popup interface uses for a more integrated experience.
 ('completion-preview-sort-function' was already present in Emacs 30.1,
 but as a plain Lisp variable, not a user option.)
 
+** Mouse
+
+---
+*** context-menu-mode now includes a "Send to..." menu item.
+The menu item enables sending current file(s) or region text to external
+(non-Emacs) applications or services.  See send-to.el for customisations.
+
 ** Windows
 
 +++

lisp/mouse.el

@@ -30,6 +30,7 @@
 ;;; Code:
 
 (eval-when-compile (require 'rect))
+(eval-when-compile (require 'send-to))
 
 ;; Indent track-mouse like progn.
 (put 'track-mouse 'lisp-indent-function 0)
@@ -393,7 +394,8 @@ not it is actually displayed."
                                     context-menu-region
                                     context-menu-middle-separator
                                     context-menu-local
-                                    context-menu-minor)
+                                    context-menu-minor
+                                    context-menu-send-to)
   "List of functions that produce the contents of the context menu.
 Each function receives the menu and the mouse click event as its arguments
 and should return the same menu with changes such as added new menu items."
@@ -536,6 +538,19 @@ Some context functions add menu items below the separator."
                   (cdr mode))))
   menu)
 
+(defun context-menu-send-to (menu _click)
+  "Add a \"Send to...\" context MENU entry on supported platforms."
+  (run-hooks 'activate-menubar-hook 'menu-bar-update-hook)
+  (when (send-to-supported-p)
+    (define-key-after menu [separator-send] menu-bar-separator)
+    (define-key-after menu [send]
+      '(menu-item "Send to..." (lambda ()
+                                 (interactive)
+                                 (send-to))
+                  :help
+                  "Send item (region, buffer file, or Dired files) to applications or service")))
+  menu)
+
 (defun context-menu-buffers (menu _click)
   "Populate MENU with the buffer submenus to buffer switching."
   (run-hooks 'activate-menubar-hook 'menu-bar-update-hook)

lisp/send-to.el

@@ -0,0 +1,233 @@
+;;; send-to.el --- send files to applications or services  -*- lexical-binding: t -*-
+
+;; Copyright (C) 1993-2025 Free Software Foundation, Inc.
+
+;; Maintainer: emacs-devel@gnu.org
+;; Keywords: send, applications
+;; Package: emacs
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This package provides commands to facilitate sending files to
+;; external applications or services.
+;;
+;; Enable `context-menu-mode' to get a "Send to..." context menu item.
+;;
+;; `send-to' uses `send-to-handlers' to pick which file(s) to send
+;; and what handler to use.
+
+;;; Code:
+
+(require 'map)
+
+(declare-function ns-send-items "nsfns.m")
+(declare-function dired-between-files "dired")
+(declare-function dired-get-filename "dired")
+(declare-function dired-get-marked-files "dired")
+(declare-function dired-move-to-filename "dired")
+(defvar shell-command-guess-open) ;; dired-aux
+
+(defgroup send-to nil
+  "Send files or text to external applications or services."
+  :group 'external
+  :version "31.1")
+
+(defvar-local send-to-handlers '(((:supported . send-to--ns-supported-p)
+                                  (:collect . send-to--collect-items)
+                                  (:send . send-to--ns-send-items))
+                                 ((:supported . send-to--open-externally-supported-p)
+                                  (:collect . send-to--collect-items)
+                                  (:send . send-to--open-externally)))
+  "A list of handlers that may be able to send files to applications or services.
+
+Sending is handled by the first supported handler from `send-to-handlers' whose
+`:supported' function returns non-nil.
+
+Handlers are of the form:
+
+\((:supported . `is-supported-p')
+ (:collect . `collect-items')
+ (:send . `send-items'))
+
+\(defun is-supported-p ()
+  \"Return non-nil for platform supporting send capability.\"
+  ...)
+
+\(defun collect-items ()
+  \"Return a list of items to be sent.
+
+Items are strings and will be sent as text unless they are local file
+paths known to exist. In these instances, files will be sent instead.\"
+  ...)
+
+\(defun send-to--send-items (items)
+  \"Send ITEMS.\"
+  ...)")
+
+;;;###autoload
+(defun send-to-supported-p ()
+  "Return non-nil for platforms where `send-to' is supported."
+  (funcall (map-elt (send-to--resolve-handler) :supported)))
+
+;;;###autoload
+(defun send-to (&optional items)
+  "Send file(s) or region text to (non-Emacs) applications or services.
+
+Sending is handled by the first supported handler from `send-to-handlers'.
+
+ITEMS list is also populated by the resolved handler, but can be
+explicitly overridden."
+  (interactive)
+  (let ((handler (send-to--resolve-handler)))
+    (unless handler
+      (error "No handler found"))
+    (dolist (item items)
+      (unless (stringp item)
+        (error "Item must be a string: %s" item)))
+    (funcall (or (map-elt handler :send)
+                 (error "Handler without :send capability"))
+             (or items
+                 (when (map-elt handler :collect)
+                   (funcall (map-elt handler :collect)))
+                 (user-error "Nothing to send")))))
+
+(defun send-to--format-items (items)
+  "Format ITEMS into a user-presentable message string."
+  (truncate-string-to-width
+   (string-join
+    (seq-map (lambda (item)
+               (if (and (stringp item)
+                        ;; Ignore url-handler-mode
+                        (and (file-local-name item)
+                             (file-exists-p item)))
+                   (format "\"%s\"" (file-name-nondirectory item))
+                 (format "\"%s\"" (truncate-string-to-width
+                                   item 35 nil nil "…"))))
+             items) " ") 70 nil nil "…"))
+
+(defun send-to--dired-filenames-in-region ()
+  "If in a `dired' buffer, return region files.  nil otherwise."
+  (when (and (derived-mode-p 'dired-mode)
+             (use-region-p))
+    (let* ((start (region-beginning))
+           (end (region-end))
+           (marked-files (dired-get-marked-files nil nil nil t))
+           (active-marks-p (if (= (length marked-files) 1)
+                               nil ;; File found at point (not marked)
+                             (not (seq-empty-p marked-files))))
+           (filenames))
+      (when active-marks-p
+        (user-error "Either mark `dired' files or select a region, but not both"))
+      (save-excursion
+        (save-restriction
+          (goto-char start)
+          (while (< (point) end)
+            ;; Skip non-file lines.
+            (while (and (< (point) end) (dired-between-files))
+              (forward-line 1))
+            (when (and (dired-get-filename nil t)
+                       ;; Filename must be in region.
+                       (< (save-excursion
+                            (forward-line 0)
+                            (dired-move-to-filename))
+                          end))
+              (setq filenames (append filenames (list (dired-get-filename nil t)))))
+            (forward-line 1))))
+      filenames)))
+
+(defun send-to--resolve-handler ()
+  "Return first supported handler from `send-to-handlers'."
+  (seq-find (lambda (handler)
+              (funcall (map-elt handler :supported)))
+            send-to-handlers))
+
+(defun send-to--ns-supported-p ()
+  "Return non-nil for macOS platform supporting send capability."
+  (and (featurep 'ns)
+       (fboundp 'ns-send-items)))
+
+(defun send-to--ns-send-items (items)
+  "Send ITEMS on macOS."
+  (ns-send-items
+   (seq-map #'send-to--convert-item-to-filename items)))
+
+(defun send-to--open-externally-supported-p ()
+  "Return non-nil for platforms supporting open externally capability."
+  (unless (boundp 'shell-command-guess-open)
+    (require 'dired-aux))
+  shell-command-guess-open)
+
+(defun send-to--open-externally (items)
+  "Open ITEMS externally (using a non-Emacs application)."
+  (unless (boundp 'shell-command-guess-open)
+    (require 'dired-aux))
+  (when (y-or-n-p (format "Open externally: %s ?"
+                          (send-to--format-items items)))
+    (dolist (item items)
+      (with-temp-buffer
+        (unless (zerop (call-process
+                        shell-command-guess-open nil (current-buffer) t
+                        (send-to--convert-item-to-filename
+                         item)))
+          (error "%s" (string-trim (buffer-string))))))))
+
+(defun send-to--convert-item-to-filename (item)
+  "Convert ITEM to a filename.
+
+Unless ITEM is a verifiable filename, save its content to a file and
+return its new timestamped filename."
+  (if (and (file-local-name item) ;; Ignore url-handler-mode
+           (file-exists-p item))
+      item
+    (let ((filename (concat temporary-file-directory
+                            (format-time-string "%F_%H.%M.%S") ".txt")))
+      (with-temp-file filename
+        (insert item))
+      filename)))
+
+(defun send-to--collect-items ()
+  "Build a list of items to send based on default context.
+
+From a `dired' buffer, chosen items are based on either of these being
+active:
+
+  - Marked files
+  - Files in region.
+  - File at point.
+
+From any other buffer, either of these two, in order of preference:
+
+  - Active region text.
+  - Thing at point (via `existing-filename').
+  - Buffer file."
+  (cond ((derived-mode-p 'dired-mode)
+         (or
+          (send-to--dired-filenames-in-region)
+          (dired-get-marked-files)))
+        ((use-region-p)
+         (list (buffer-substring-no-properties
+                (region-beginning)
+                (region-end))))
+        ((thing-at-point 'existing-filename)
+         (thing-at-point 'existing-filename))
+        ((buffer-file-name)
+         (list (buffer-file-name)))))
+
+(provide 'send-to)
+
+;;; send-to.el ends here

lisp/term/ns-win.el

@@ -214,6 +214,7 @@ The properties returned may include `top', `left', `height', and `width'."
 (defvaralias 'mac-right-option-modifier 'ns-right-option-modifier)
 (defvaralias 'mac-function-modifier 'ns-function-modifier)
 (declare-function ns-do-applescript "nsfns.m" (script))
+(declare-function ns-send-items "nsfns.m" (items))
 (defalias 'do-applescript 'ns-do-applescript)
 
 ;;;; Services

src/nsfns.m

@@ -3670,6 +3670,57 @@ The position is returned as a cons cell (X . Y) of the
   return Qnil;
 }
 
+#ifdef NS_IMPL_COCOA
+
+DEFUN ("ns-send-items",
+       Fns_send_items,
+       Sns_send_items, 1, 1, 0,
+       doc: /* Send a list of items to macOS applications or services. */)
+       (Lisp_Object items)
+{
+  CHECK_LIST (items);
+
+  NSMutableArray *sent = [NSMutableArray array];
+  for (Lisp_Object tail = items; CONSP (tail); tail = XCDR (tail))
+  {
+    Lisp_Object elt = XCAR (tail);
+    if (!(STRINGP (elt)))
+    {
+      signal_error ("Element not a string", elt);
+    }
+    BOOL isDir;
+    if ([[NSFileManager defaultManager] fileExistsAtPath:@(SSDATA(elt)) isDirectory:&isDir]) {
+      [sent addObject:[NSURL fileURLWithPath:@(SSDATA(elt))]];
+      continue;
+    }
+    [sent addObject:@(SSDATA(elt))];
+  }
+
+  struct frame *frame = SELECTED_FRAME ();
+  struct window *window = XWINDOW (selected_window);
+
+  int text_area_x, text_area_y, text_area_width, text_area_height;
+  window_box (window, TEXT_AREA, &text_area_x, &text_area_y,
+              &text_area_width, &text_area_height);
+
+  int x = text_area_x + window->phys_cursor.x;
+  int y = text_area_y + window->phys_cursor.y;
+
+  NSPoint point = NSMakePoint(x + FRAME_COLUMN_WIDTH (frame) / 2,
+			      y + FRAME_LINE_HEIGHT (frame) + 10);
+
+  EmacsView *view = FRAME_NS_VIEW (frame);
+  NSSharingServicePicker *picker = [[NSSharingServicePicker alloc] initWithItems:sent];
+  [picker showRelativeToRect:NSMakeRect(point.x - 1, point.y - 1, 2, 2)
+		      ofView:view
+	       preferredEdge:NSRectEdgeMaxY];
+
+  return Qnil;
+}
+
+
+#endif /* NS_IMPL_COCOA */
+
 /* ==========================================================================
 
     Class implementations
@@ -3902,6 +3953,9 @@ - (Lisp_Object)lispString
   defsubr (&Sns_set_mouse_absolute_pixel_position);
   defsubr (&Sns_mouse_absolute_pixel_position);
   defsubr (&Sns_show_character_palette);
+#ifdef NS_IMPL_COCOA
+  defsubr (&Sns_send_items);
+#endif
   defsubr (&Sx_display_mm_width);
   defsubr (&Sx_display_mm_height);
   defsubr (&Sx_display_screens);